common k7000 issues - common repairs

@security0001 I guess doesn't sell a pot kit for the deflection board, only remote board, but I'm sure he can unearth a H. Hold replacement. but you probably don't need it, I would think if it were bad you would just have a scrambled mess on the screen. LOL it is strange you went to both extremes and couldn't get the sync to break. if you have a vertical rolling picture, that's V. Hold. if you haven't tried that yet.
Welp, I took the chassis out. It looks like it has newer caps so I didn't end up using the kit I bought. I replaced the h-hold pot and resoldered the video input pins. Thought I saw what might have been a broken trace on pin 9, so I touched that up.

Plugged it all back in and it's the same, maybe slightly worse.
Is it possible this isn't even a monitor issue but a board issue?

Why would the mistercade not have this issue?

[Edit: I plugged in my EZ 2-Way JAMMA switcher with point blank 2 plugged in to the main board, MiSTercade on the extension board and when I use the MiSTer with this configuration, it too has the wavy edges and distortion. It's actually way less stable than the PB2.]

Not sure what to try next! This thing used to work just fine before I (tried to) bring it into my basement. (that's a whole 'nother story, but it's back in the garage :D)

[Edit2: I found this thread that seems to be the exact same thing I have (even the same game): https://www.aussiearcade.com/topic/83587-crt-monitor-display-with-wiggly-lines/ different monitor and the thread ends without resolution.
After seeing this I started focusing on video ground. I tried jumping pins 2+14 on my PB2 board but it seemed worse. I disconnected video ground from my JAMMA harness and while it looks worse, it doesn't look too much different, just wavier. I was going to run a new wire from my JAMMA connector to my chassis but I don't have the right crimp connector for the video harness. Tried just wrapping around the pin on the chassis but still wavy. I do notice when I touch that end of the wire to different pieces of metal on the cab I do see the waves change. It's the only thing I've been able to do to reliably affect the waviness. ]

[Edit3: decided to recap it. My arcadepartsandrepair kit says c20 is 10uf @ 50v. The c20 I'm pulling is 100uf @ 10v and it looks like some damage next to it on the board. I added a picture]
 

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Progress!
After recapping, the issue has gone away!
Had some weirdness with how the vertical size pot was behaving but I believe I fixed it with the 50/60hz pot. It was like once the picture filled 90% of the screen any additional size blew it up way too big.

I am seeing some weirdness when I jiggle the arcade where the picture jumps. I think I have a weak video ground and will need to re-wire that.
 
I have been having fun with my 9K7704, which is a 9" monitor for a Pit Boss Superstar bar top game. This morning the monitor wouldn't come on, well it did one more time after a number of power cycles then dead. I ended up finding that I was pushing 158v on B+ and started thinking about parts. Then found that cool flow chart and pulled one leg of the D10 shutdown diode and I got picture.

This PCB has been worked on before and C57 had been replaced. Its appears the pad had lifted and the tech put in a jumper line along the messed up trace/pad. It seemed a bit nasty, so I cleaned it up and reflowed it. Then I cleaned up/reflowed some other areas, like R101. Put D10 back into place and B+ was back at its normal level! Though I lost red to the monitor but that ended up being me pulling the connector off and loosening the male connector from the PCB! Cleaned that up, reflowed it, and red came back!

I still have darkness/black-ish bars on the left side but I had that before. So have ordered from Arcade Parts and Repair a Cap Kit. I also got a Filter Cap and Fly Back with this order, though I don't think I'll need to install those parts. Assuming I don't, they'll be nice to have in "stock".

The worst part of all of this is that I shot myself in the foot!! I was pulling the monitor again and let things slip and I busted VR7 10k Contrast control. So whatever flavor trimmer pot I end up getting, I got to make the shipping worth while. So I'll order more parts to have in "stock", so I'll get: 2K OHM TRIMMER (Shutdown Pot), STR3123 (Regulator), 1N4007 (Rectifier Diodes), and 6.8K OHM 3 WATT (ex R101) to have on hand.

Can't believe I broke VR7 Ugh - Stupid Me!
 

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HOLY BATMOBILE.

O.K., I've got a K7000, same thing. HV shutdown, everything looks good, recapped, new (er) looking flyback, replaced Hot, replaced Voltage Regulator, etc. (I think this may have more to do with the Voltage regulator being new now than anything, but I digress).

HV Shutdown. Saw your post. This was a newer one with C36, AND C69. C36 was .0036, C69 was the usual 6100pf. Upon comparing THIS board with an older... the only difference in this and the 4 legged version, was that they used two caps. The original C36 was 6100, but now they've got two in there. I'm sure it worked that way perfectly originally... this has what appears to be a newer flyback, I didn't install it, but I get the idea that somebody did, got disgusted that it didn't fix it, and left it in there. Anyways.

I cut C36 out, and simply jumpered the trace from C69 over to where C36 was. The other end was already tied together by the traces. Basically, I connected the two pins together like the 4 legged cap would do, leaving the 6100pf still mounted in C69, C36 empty, and a small jumper to connect it over to C69.

Fired right up! I've got a Vertical problem now, but this thing was sitting pretty at 165 v for the last two days, and now I've got a perfect 130.
@zenomorp Need A video on this. Hint Hint
I never thought 💭 c36 would go out of spec. For some reason I thought they just shorted out. I've only ever seen a few chassis"s with 2 CS caps. I always see the 4 post ones
 
Doing a K7000 Repair-A-Thon on a lot of 5 7000s I recently acquired. First video is up. I decided to make it more of a complete tutorial on all the problem areas to inspect, test, what to look for, what readings you should get, how to repair bad/oxidized pads, and how to do the light bulb test. Kind of a reference for beginners. Hopefully, it helps some people out.

 
Posting this here instead of it's own thread. I've said it before and I'll say it again. Inspection and reflow is key. Eugene from Eldorado Games brought me this "rebuilt" 19" K7000 to look over and fix if needed. Gave it some inspection, nothing looked bad that would keep it from working (although I did see some issues that I will mention shortly), so I fired it up and it seemed to work fine. Took it back off the tube and got to work. First things I noticed were the HOT and the Voltage regulator were both the incorrect parts. Someone installed an STR3130 instead of the proper STR3123. The last three numbers are the regulated voltage. 130v is for the 25." 123v is for the 19." Some knucklehead installed a 130v regulator on this 19." The HOT was a D1399. Was supposed to be a D1398. Does the 1399 work? Sure. But it's supposed to be a 1398. Installed the correct components and moved on.

Always. ALWAYS remove the solder from R101 and R89 to make sure the pads are not oxidized. Almost every K7000 out there is like this. The pads get oxidized and when you try and reflow the joints, the existing solder just flows right up the iron tip and nothing will flow back onto the pad. You need to remove the oxidation with a fiberglass pen or any other means you want to use. I also recommend bridging the joints to provide added heat dissipation to prevent this from happening in the future. Those resistors run very hot and causes these issues. It can also happen with D18, as was the case here. Perform the same procedure. It's also a really good idea to clean up the legs of the oxidized components with the fiberglass pen as well to ensure a good joint. Not just on the pad, but on the leg(s) as well.

This chassis also only had about 6 caps replaced. C56 wasn't even the correct rating. Was supposed to be 22uf and someone installed a 33uf. I just don't know sometimes. Went ahead and did a fill kit along with reflowing everything else. It already had a replacement flyback as well. After getting all the joints fixed, installing the proper parts, and getting it all reflowed...it's adjusted and working great. On to the next one because it never ends. Here's a link to the sanding pen I use...

 

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Is this fiberglass pen you always use?

There are a few options for fiberglass pens. The cheap red plastic ones on ebay are fine for $7:


One will last you a long time, and if you do use it up you can just get another.

If you do repairs regularly like me, I invested in an Eraser brand pen, which are used by auto repair/detailing guys. It's much better quality, lasts a lot longer, is a little more coarse (which saves time), but is much more expensive. (And you can't buy single refills, they make you buy a box of 25 for $150.) But it took me many years of almost daily use to use up one insert, as they last a lot longer than the red plastic pens:



I can't speak for the one zenomorp uses, but it looks decent. Realistically any of them will work. If you can get single replacement inserts, it might be convenient to get one or two spares. But you'll never use 20. In my experience, the mechanisms in the red pens can sometimes wear out eventually. But they're basically disposable, so it's easier to just buy another one for $7.
 
There are a few options for fiberglass pens. The cheap red plastic ones on ebay are fine for $7:


One will last you a long time, and if you do use it up you can just get another.

If you do repairs regularly like me, I invested in an Eraser brand pen, which are used by auto repair/detailing guys. It's much better quality, lasts a lot longer, is a little more coarse (which saves time), but is much more expensive. (And you can't buy single refills, they make you buy a box of 25 for $150.) But it took me many years of almost daily use to use up one insert, as they last a lot longer than the red plastic pens:



I can't speak for the one zenomorp uses, but it looks decent. Realistically any of them will work. If you can get single replacement inserts, it might be convenient to get one or two spares. But you'll never use 20. In my experience, the mechanisms in the red pens can sometimes wear out eventually. But they're basically disposable, so it's easier to just buy another one for $7.
That is not actual fiberglass. Those are closer to a very rough bristle. They are meant for cleaning edge connector and such. When trying to remove solder mask, they do nothing. I've tried them.
 
That is not actual fiberglass. Those are closer to a very rough bristle. They are meant for cleaning edge connector and such. When trying to remove solder mask, they do nothing. I've tried them.


The ones sold as fiberglass are fiberglass. (You can tell when it gets embedded in your skin.) They're just very fine. There are others that look the same that are sold as nylon, but I've never tried those.

The fiberglass ones actually come in a couple of coarsenesses, which are not labeled. But I have one that is very coarse (even more than my Eraser pen), and a bunch of the soft ones. But yes, most of them are pretty soft, and won't remove solder mask.

For removing solder mask, I just scrape it off with my Exacto, then polish with the pen if needed.
 
The ones sold as fiberglass are fiberglass. (You can tell when it gets embedded in your skin.) They're just very fine. There are others that look the same that are sold as nylon, but I've never tried those.

The fiberglass ones actually come in a couple of coarsenesses, which are not labeled. But I have one that is very coarse (even more than my Eraser pen), and a bunch of the soft ones. But yes, most of them are pretty soft, and won't remove solder mask.

For removing solder mask, I just scrape it off with my Exacto, then polish with the pen if needed.
I like my Eurotool (https://www.amazon.com/gp/product/B0019V18D2) and dang those glass fiber are annoying when they get in your skin. I use them to remove the oxidation on Galaga custom chips too.
 
How can I test R105 for the degaussing coil? I don't hear the "sound" of the degaussing when I power up and I wonder if it is not working well. I measured the voltage to the coil and it appears to reach about 50V for less than a second. I was using a DMM where I fixed the range so I could get a reading as quickly as possible.

My PTC is kind of cracked open and very hot to touch ;)
 
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